How to resize an image on iPhone and Android

The quickest way on any phone

Open a resize tool in your phone’s browser. Nothing to install, and it works the same on iPhone and Android:

1. Open the image compressor in Safari or Chrome.
2. Tap choose files and pick the photo from your gallery.
3. Type the size you need in KB, or pick one (for example 50 KB or 100 KB).
4. Tap Download. The smaller photo goes to your Downloads (Android) or the Files app (iPhone).

The photo is processed on your phone; it is never uploaded. If a form asks for a size in cm or pixels instead, use resize image in cm. If it rejects your iPhone photo because it is HEIC, convert it with HEIC to JPG first.

The rest of this guide shows how to do it with the phone’s own apps.

On iPhone

The Photos app has no “resize” button. These are the built-in ways around that.

Resize with the Shortcuts app

Shortcuts comes with every iPhone and has a Resize Image action. Set it up once:

1. Open Shortcuts and tap + to make a new shortcut.
2. Tap Add Action, search for Resize Image and add it.
3. Tap Image in the action and choose Shortcut Input. Set the width you want, for example 1000 (the height follows).
4. Add the Save to Photo Album action under it.
5. Open the shortcut’s settings (the ⓘ button) and turn on Show in Share Sheet. Name it, for example “Resize photo”.

From now on: open a photo in Photos, tap Share, and choose Resize photo. The smaller copy is saved to your library; the original stays. Menu names can differ a little between iOS versions.

Send a smaller copy with Mail

When you share photos to the Mail app, iPhone often asks for an image size before sending: Small, Medium, Large or Actual Size. Choose Small or Medium to send a much lighter file. This only changes the emailed copy, and you cannot pick an exact size.

Crop in Photos

Tap Edit → the crop button, and drag the corners. Cropping cuts away parts of the picture, so the result has fewer pixels and a smaller file. It is useful before a resize (crop to your face for a form photo), but it is not a way to set a size.

Take new photos as JPG

iPhones save photos as HEIC, which many forms refuse. To get JPG from now on: Settings → Camera → Formats → Most Compatible. Photos already taken stay HEIC; convert those when you need to.

On Android

Samsung Galaxy phones

The Samsung Gallery app can resize:

1. Open the photo in Gallery and tap Edit (the pencil).
2. Tap ⋮ (More options) at the top right and choose Resize.
3. Pick a percentage and tap Done.
4. To keep the original, tap ⋮ → Save as copy; Save replaces it.

The option is missing on some older models and software versions. It can only make photos smaller, not bigger.

Other Android phones

Google Photos and many other gallery apps can crop but cannot resize to a size you choose. Use the browser tool above, which works in Chrome on any Android phone, or a gallery app from your phone’s maker if it has a resize option.

How small should the photo be?

It depends on what the photo is for. For upload forms with a KB limit, this is what our sample phone photos came to:

If a form gives a size in cm, such as 3.5 × 4.5 cm, it also needs a DPI to become pixels: 3.5 × 4.5 cm at 200 DPI is 276 × 354 px. The resize image in cm tool does that maths and keeps the file inside your KB range.

Common questions

Does resizing a photo on my phone lower the quality?

Making it smaller keeps it sharp at its new size. What looks bad is a photo squeezed into a tiny KB limit at full size; a KB-based tool avoids that by making the photo smaller instead of blocky.

Why is my photo still too big after resizing?

Some apps keep a very high quality when they save, so the file stays large even with fewer pixels. Set the KB limit directly in a tool that aims for it, or resize to a smaller width.

Can I resize a signature on my phone?

Yes. Take a photo of your signature on white paper, then use signature resize, which also cleans the background to white and keeps the file in a range like 10 to 20 KB.